Treatment of hydrocarbons



Qcpze, 1943. l.. s, KASSEL' 2,332,577

TREATMENT 0F HYDRCARBONS Filed Nov. a, 1940 Aun/LATE DEPRoPAA/.lS/NGZONE Patented Oct. 26, 1943 TREATMENT F HYDROCRBONS Louis S; Kassel,Chicago, Ill., assigner to Universal Oil Products Company, Chicago,Ill., a corporation of Delaware `Application November 8, 1940, SerialNo. 364,763

FFICE 7 Claims.

This invention relates to a process for producing substantiallysaturated gasoline of high antiknock value from parans and olei'lns.

More specifically the invention is concerned chloride used inisomerization is recovered and MiO-683.4)

recycled. The process will be described with particular reference toisomerization of normal butane to isobutane by aluminum` .chloridecatalysts in the presence of hydrogen chloride and with a combinationprocess comprising catalytic hydrogen and to alkylationof isobutanebybuisomerization of normal butane to isobutane in tenes but it isapplicable also to the isomerization the presence cf an aluminumchloride-containof other normal and mildly branched chain paringcatalyst, hydrogen chloride, and a permanent ain hydrocarbons includingn-pentane, hexanes, gas, followed lby alkylation of isobutane by buandhigher parafns, and to the alkylation of tenes in the presence ofsulfuric acid. l0 the resulting branched chain paraliinv hydrocar- Inone specific embodiment thepresent invenbons with normally gaseous andliquid olens in tion comprises a process for producing substan- 4 thepresence of catalysts as hereinafter set forth. tially saturatedhydrocarbon fractions of gasoline Isomerization of normal butane may beefboiling range and high antiknock value which fected by contacting thishydrocarbon in the comprises commingling a butane-butene fracpresence ofhydrogen chloride with a granular tion with a fraction formed in theprocess and composite comprising substantially anhydrous containingisobutane, hydrogen, and hydrogen aluminum chloride or a mixture ofsubstantially chloride; subjecting the comming'led mixture to anhydrousaluminum chloride with a chloride of alkylation in the presence ofsulfuric acid to form iron, copper; zinc, or zirconium preferably supanalkylation product; separating said product ported by a granular carriersuch. as activated into a mixture and used sulfuric acid;fractioncarbon, pumice, various types of fullers earth and vating saidmixture into a substantially saturated clays, particularly those of themontmorillonite alkylate and an unconverted fraction comprising andbentonite types either raw or acid treated, essentially butanes, smallamounts of lower boildiatomaceous earth, a silica-alumina composite, ingparadns, hydrogen, and hydrogen chloride; unglazed porcelain,fire-brick, and in general rerecycling a portion of said unconvertedfraction fractory porous substances which have substanto mix with thecommingled mixture being subtially no .chemical reactivity with aluminumjected to alkylation; subjecting a second portion chloride, ironchloride, copper chloride, zinc chloof said unconverted fraction toseparation to sepride, and/or zirconium chloride. arate hydrocarbonsboiling lower than butanes In the vpresence of such composite catalystsfrom a substantially butane mixture; subjecting normal butane may beconverted into approxito a further separation said substantiallyv butanemately 30-60% isobutane per pass when utilizing mixture in admixturewith a third portion of a temperature in the approximate range of saidunconverted fraction comprising essentially 10D-650 F., and preferablyunder a pressure in l butanes, small amounts of lowe'r boiling par- 35the range of substantially atmospheric to apaiiins, hydrogen, andhydrogen chloride to sepaproximately 3000 pounds per square inch andrate normal butane from isobutane, small 'preferably in the rangeof50-1000 pounds per amounts of lower boiling parains, hydrogen squareinch. While inert gases, such as nitrogen, chloride, and hydrogen;withdrawing a portion lmay sometimes be employed alternatively in proofsaid normal butane from the system; conduct- 40 ducing the necessarypressure, experiments have ing the remainder of said normal butane andthe shown that hydrogen is preferable,y as its presremainder of saidunconverted fraction to conence in an amount between about 0.5 and 2.0mole tact with an isomerzing catalyst in the presence per cent of thehydrocarbons present seems to of hydrogen and/or hydrogen chlorideproduced minimize undesirable side reactions involving dein the processor introduced from an outside composition rather than the desiredisomerizasource to form a mixture containing a substantion. i ns1proportion of isobutane; cooling and con- There are Several alternativecatalysts comdensing said mixture without substantial reduc- DI'lSingaluminum ChlOIlde 01' mixtures 0f 2ll1. tion of pressure in order tosubstantially dissolve mlnum Chloride With chlorides 0f' 11011, COPDer,hydrogen chloride and hydrogen in the con- Zinc 91 zirconium Supported0n inert' carrying densed butanes; combining said mixture with thematellals which may be employed to effect the isobutane fractiondescribed above; and conductlsomelization Siep of the present. inventioning the resulting mixture and an added butane-v While many 0f theseCarl-ying materials may be butene fraction to said alkylation in thepresence used more 0r less interchangeably some are more of sulfuricacid, effective than others and it is not intended to The combinationprocess of the present invenimply thatv all carriers are denitelyequivalent. tion is particularly advantageous on account of AlSO, il?frequently happens that 011e ljype 0f earits relatively smallvfractionation requirements Tiel' 01' support is'better for use with s''given and the simplied method by which the hydrogen Catalyst Centaihingmetal ehloldes, depending upon the ratio of metal cl. iorides to supportfound experimentally to be best for the vfurtherance of the butane orparain isomerizing reaction. Accordingly,Y it is not to be implied thatthe supports can at all times be used interchangeably. Extensiveexperiments have indicated that best results are obtained when a minorpercentage of hydrogen chloride is present in the reaction and thisnecessary amount of hydrogen chloride, generally from approximately 0.5to 20% by weight of the parafln charged, may be introduced directly froman outside source or produced in the system as by the action of usedsulfuric acid upon salt.

The products withdrawn from the isomerization step containing hydrogenchloride, hydrogen, normal butane, isobutane, and also minor amounts ofmethane, ethane, propane, and pentanes may be cooled to liquefy thebutanes and to dissolvetherein desired proportions of hydrogen andhydrogen chloride. Gases which remain undissolved may be discharged andthe liquefied material may be commingled with a butene-containingfraction and then conducted to alkylation in the presence of sulfuricacid which may comprise a mixture of fresh acid and recycled acidpreviously used in the process. The addition of the butene-containingfraction i`s preferablyv so controlled that the olefin content of thecommingled mixture does not exceed approximately 10% of the isoparafnhydrocarbons being conducted to alkylation.

Alkylation of isobutane and of other isoparaflins by `olens andparticularly by normally gaseous oleflns as, for example, butenes, maybe eiected in the presence of sulfuric acid of approximately 90100% orhigher concentration at a temperature in the approximate range of -15 to200 F. under a pressure lsufficient to maintain substantially liquidphase operation and generally at a pressure in the range of fromsubstantially atmospheric to approximately 1000 pounds per square inch.It is preferable that mixtures being subjected to alkylation contain amolal excess ofthe isoparafn in order to substantially preventpolymerization and to keep the alkylating catalyst active for arelatively long period of time. Good yields of substantially saturatedalkylation products are generally obtained when employing, for example,from approximately 4 to 15 or more molecular proportions of isoparainnper molecular proportion of olen present in the mixture being subjectedto alkylation.

The use of a combination of butane or parain isomerization andalkylation, according to the process of this invention, has theadvantage#` that saturated gasoline of high octane number may beproduced without the necessity of hydrogenation which is inherent in theformation of gasoline, which may be used for aviation purposes, bypreviously used processes involving dehydrogenation of butane,polymerization of the resultant butenes to iso-octenes, andhydrogenation of the iso-octenes to iso-octanes.

The isomerizing and alkylating catalysts hereinabove described which maybe used for effecting these respective reactions are not necessarilyequivalent in their actions and the conditions of temperature, pressure,and time employed for any given isomerization or alkylation reaction aredetermined bythe catalyst, the hydrocarbons involved, the composition ofthe reaction mixture, and by other factors.

For the purpose of illustrating the combination of steps characteristicofthe present invention, the accompanying drawing shows diagrammaticallymeans embodying one specic process ow utilizable' for producing gasolineof high octane number from a butane-butene fraction.

Referring to the drawing, a butane-butene fraction separated fromproducts obtained in petroleum cracking, in dehydrogenation of butane,or from any other source, is introduced through line I to line 2,therein commingled with a fraction containing isobutane, hydrogen, andhydrogen chloride and obtained in the process as hereinafter set forth,and the commingled mixture is then introduced to alkylating zone 3containing sulfuric acid as alkylating-catalyst.

Alkylating zone 3 comprises a suitable, reactor provided with adequatemeans for mixing, heating, and/or cooling to maintain a desiredoperating temperature generally in the approximate,

range of -15 to 200 F. This operation is effected under sufficientpressure that substantial proportions ofthe hydrogen and hydrogenchloride are kept in solution by the liquefied butanes. From alkylatingzone 3 the products comprising essentially a substantially saturatedalkylateunconverted butanes, and usedk sulfuric acid are conductedtherefromfthrough line 4 to acid separating zone 5 of suitable designfor separating used sulfuric acid from a substantially saturatedhydrocarbon fraction containing the alkylation product. Used sulfuricacid is withdrawn'frcm acid separating zone 5 through line 6 and thereinrecycled to line 2, alreadymentioned, through which butanes and butenesare conducted to alkylation. When desired, a portion of the-total ialkylation product bein-g discharged from alkylating zone 3 through line4 may be conducted therefrom through line 'I to line 6 and then recycledto further alkylat'ion treatment.

The hydrocarbon fraction separated-in acid separating zone 5 visconducted therefrom through line 8 to debutanizing zone 9 whichcomprises fractional distilling equipment of adequate design by which asubstantially saturated alkylate is separated as bottoms from anoverhead condensate comprising essentially normal butane, isobutane,hydrogen, and hydrogen chloride. The substantially saturated alkylate isWithdrawn from debutanizing zone 9 through line I0 to storage or to asubsequent fractionating treatment, not shown, to separate hydrocarbonsof desiredv boiling range. Theoverhead condensate separated from thealkylate in debutanizi'ng zone 9 is conducted therefrom through line IIfor further use as hereinafter set forth. When desired, a portion of thetotal alkylation product is conducted from line 8 through lines I2 andI1 to line I through which butanes and butenes are charged toalkylation.

A portion of the used sulfuric acid being withdrawn from acid separatingzone 5 through line 6 is discharged from the system through line I3.Part of the used sulfuric acid being conducted through line I3 is passedthrough branch line I l to hydrogen chloride-generating zone I5 to whichsalt is admitted through line I6. drogen chloride resulting from theinteraction of the used sulfuric acid and the added salt is conductedfrom hydrogen chloride-generating zone I5 through line I'Ito line I inwhich the charged butane-butene fraction is conducted to alkylation. Itis preferable to introduce the hydrogen chloride on the suction side ofthe pump by which 'the hydrocarbons are brought to the pressure used inalkylation which is generally in the approximate range of 50-1000 poundsper square inch although higher and lower pressures may be used also.The hydrogen chloride may also be introduced to the process preferablyat some other suitable low pressure point of the system.. The rate ofaddition of hydrogen chloride is controlled so as to make up for itsunavoidable losses from the system. Sodium sulfate formed in `hydrogenchloride generating zone I may be discharged therefrom through line I8.

A portion of .the overhead condensate passing through line II asaforementioned and comprising essentially isobutane, normal butane.hydrogen chloride, and hydrogen is conducted through lines I9 and 2 toalkylating treatment in alkylating zone 3. Fresh sulfuric acid isintroduced to the alkylating step of the process through line to line 6already mentioned.

A second portion Vof the overhead condensate passing through line II isconducted therefrom through line 2| to separating zone 22 whichcomprises fractional distilling equipment -of adequate desi-gn forseparating normal butane from a lower boiling fraction comprisingessentially isobutane, hydrogen,l and hydrogen chloride. 'The normalbutane is directed from separating zone 22 through line 23 to line II,already mentioned, and thence through a suitable preheater, ynot shown,to isomerizing zone y25. When cle-- sired, normal butane is dischargedfrom line 23 through branch line 24 to storage or to other use. Fromseparating zone 22 the fraction -comprising essentially isobutane,hydrogen, and hydrogen chloride is conducted through lines 26, 6, and 2to further alkylating treatment. A portion of the overhead condensateinline Il may be directed to isomerization zone 25 together with thenormal butane fraction produced in separating zone 22.

Isomerizing zone 25 comprises a reactonof suitable design containing asfiller a composite of anhydrous aluminum chloride and a substantiallyinert carrier operated at a temperature within the approximate limits of100 and 650 F. and under a pressure preferably between about 50 andabout 1000 pounds per square inch although the pressure may range fromsubstantially atmospheric to approximately 3000 pounds per square inch.The condensate being conducted to isomerizing zone 25 by means of line p,Il is commingled therein with hydrogen introduced from an outsidesource or produced by the action upon a metal of a portion of the usedsulfuric acid. For the latter purpose used sulfurie acid is conductedfrom line I3 through line 21 to hydrogen-generating zone 28 containing ametal such as iron or zinc introduced conveniently by Way of line 29.Hydrogen so formed may be passed from hydrogen-generating zone 28through line 30 to line II, already mentioned, through which a mixtureof butanes, hydrogen chloride, and hydrogen is being conducted toisomerizing zone 25. When desired, hydrogenl from an outside source maybe admitted through line 3l to line 30. Metal sulfate formed by thehydrogen-generating action in hydrogen-generating Zone 28 may bedischarged therefrom throughfline 32 to storage or to vother use.

The mixture of isobutane, normal butane, hy-

4process is preferably operated under a pressure sufficient to maintainin solution a substantial proportion of the hydrogen present.

It is necessary to prevent excessive accumulation of propane and lighterhydrocarbons in the substantially butane mixture beingsubjected toisomerization and alkylation treatments. Such depropanization is carriedout by subjecting to depropanization a part of the overhead condensatebeing conducted from debutanizing zone 9 through line II to isomerizingzone 25. Thus a third portion of the overhead condensate is passed fromline Il through line 3B to depropanizing zone 31 which comprises afractional distilling column by which butanes are Separated from lowerboiling materials such as a mixture of propane, hydrogen, and hydrogenchloride. Said mixture is discharged from depropanizing zone 31 throughline 38 while the butanes are returned from depropanizing zone 31through line 39 to line 2| and are thence conducted to furtherseparating, alkylating, and/or isomerizing treatment.

Thus only the hydrogen chloride contained in the' relatively smalldepropanizer charge will be lost from the process While that containedin the material recycled directly to alkylation, isomerization and/orvto separation into isobutane and normal butane will be available in theisomerizing and alkylating steps already mentioned.

Alternatively a portion of the overhead condensate may bedischarged fromthe system through line I I and branch line 40 thus simultaneouslyeliminating accumulation of propane and excess butanes. This alternativemethod of disposing of propane avoids the operation of two distillingcolumns but has the disadvantage that the loss of hydrogen chloride isconsiderableand that the butane withdrawn from the process contains asubstantialproportion of isobutane.

The process of this invention may thus be used for converting abutane-butene fraction or individual'butanes and butenes derived fromany source into substantial yields of substantially saturatedhydrocarbons of gasoline boiling range and high octane number.

The. following specific example is introduced as representative ofresults expected from the drogen, vand hydrogen. chloride present inisomhydrogen chloride an present in relatively small tene, 9.1%

process hereinabove described, although with no intention of undulylimiting the generally broad scope of the invention:

100 `volumes of a butane-butene fraction containing approximately 10mole per cent isobutene, 3,2% normal butene, 18% isobutane, and 40%normal butane is commingled with approximately 250 volumes ofa totalbutane mixture both that formed and recycled in the process andcontaining approximately isobutane, and 15% normal butane. The resultingcommingled mixture containing approximately 2.9% isobunormal butene,66.0% isobutane, 22.0% normal butane and small amounts of added hydrogenand hydrogen chloride is subjected to contact with sulfuric acid of 98%concentration at 45 F., under a pressure of 106 pounds per other portionis separated into .normal butane and a lower boiling fraction comprisingessentially isobutane, hydrogen, and hydrogen chloride. The latterfraction is recycled to alkylation while the normal butane fraction issubjected to isomerization in the presence of hydrogen, hydrogenchloride, and a composite of 33% L by Weight of aluminum chloride and67% by weight o f activated charcoal, said composite being utilized as agranular ller in a reactor maintained at a temperature of approximately250 F., and under a pressure of approximately 250 pounds per squareinch. The isomerization product generally consisting of approximately67% isobutane and 33% normal butane is condensed under pressure tosubstantially absorb the desired amount of hydrogen chloride present andform a lmixture for commingling with the butane-butene fraction beingcharged to alkylation.

'I'he character of the process of the present invention and particularlyits commercial value` are evident from the preceding specification andexample given, although neither section is intended mal butane.

ing the resulting alkylation products including the hydrogen andhydrogen halide to separate an alkylate from. the remaining productsofthe,Y alkylation treatment, and supplying atleast a portion of thelatter to the isomerizing step.

.3. The process ofclaim 1 further characterized in that vsaid normalparaffin comprises norbons which comprises subjecting a normal parto beunduly limiting in its generally broad scope. f

I claim as my invention:

1. A process for the conversion of hydrocarbons which comprisessubjecting a normal paraffin fraction to contact with a metal halidecatalyst under isomerizing conditions of temperature and pressure and inthe presence of hydrogen and hydrogen halide to form 'branched-chainparafiin, subjecting the .resulting ,conversion products including saidhydrogen and said hydrogen halide to cooling and condensation withoutsubstantial reduction of pressure to condense the branched-chain parainand unconverted normal parafiin and to dissolve a substantial' portionof the hydrogen and hydrogen halide in the condensate, combining saidcondensate with an olefin-containing hydrocarbon fraction and subjectingthe mixture to alkylation.

2. A process for the conversion of hydrocarbons which comprisessubjecting a normal paran fraction to -contact with a metal halidecatalyst under isomerizing conditions of temperature and pressure and inthe presence of hydrogen and hydrogen halide to form branched-chainparailin, subjecting the resulting conversion products including saidhydrogen and said hydrogen halide to cooling and condensation withoutsubstantial reduction of pressure to condense the branched-chain parainand unconverted ,normal parafn and to dissolve a substantial portion ofthe hydrogen and hydrogen halide in the condensate, combining saidcondensate With an olefin-containing hydrocarbon fraction and subjectingthe mixture to alkylation, fractionatail-in fraction to contact With ametal halide isomerizing catalyst under isomerizing conditions oftemperature and pressure and in the presence of hydrogen halide to formbranched-chain paraiiins,` subjecting the resulting conversion productsincluding said hydrogen halide to cooling and condensation Withoutsubstantial reduction of pressure to condense the same and dissolve inthe resultant condensate a substantial portion of the hydrogen halide,'combining the resultant condensate with an olefin-containing vfractionand subjecting the mixture-to alkylation.

6. A process for the conversion of hydrocarbons which comprisessubjecting a normal paraln fraction to Contact with a metal halideisomerizing catalyst under isomerizing conditions of temperature andpressure and in the presence of hydrogen halidefto form branched chainparaiins, subjecting the resulting conversion .products including thehydrogen'halide to cooling and condensationwithout substantial reductionof pressure to condense the branched-chain paranand unconverted normalparaffin and to dissolve in the resulting condensate at least a portionof the hydrogen halide, combining the resultant condensate with anolefin-containing `fraction, subjecting the mixture to alkylation,separating normal parailins and hydrogen halide from the remainingproducts of alkylation and supplying the normal paraflins and hydrogenhalide to the isomerizing step.

7. A process for the conversion of hydrocarvbons which comprisessubjecting a normally gaseous mixture comprising-isobutane, normalbutane and butenes' to alkylation, separating normalA butane from theresultant conversion products, subjecting said normal butane to contactwith a metal halide isomerizing catalyst under isomerizing conditions oftemperature and vpressure and in the presence of hydrogen halide to formadditional isobutane, subjecting the products of the isomerizingtreatment including the hydrogen halide to cooling and condensationwithout substantial reduction of pressure to condense the additionalisobutane and unconverted normal butane and to dissolve at least aportion of the hydrogen halide in the resulting condensate and supplyingthe condensate thus formed tothe alkylation step.

LOUIS S." KASSEL.

